Continuous Glucose Monitoring in Interstitial Subcutaneous Adipose Tissue and Skeletal Muscle Reflects Excursions in Cerebral Cortex

  1. Jannik Kruse Nielsen,
  2. Christian Born Djurhuus,
  3. Claus Højbjerg Gravholt,
  4. Andreas Christiansen Carus,
  5. Jacob Granild-Jensen,
  6. Hans Ørskov and
  7. Jens Sandahl Christiansen
  1. From the Medical Department M (Endocrinology and Diabetes) and Medical Research Laboratories, Århus Sygehus, Århus University Hospital, Århus C, Denmark
  1. Address correspondence and reprint requests to Claus Højbjerg Gravholt, MD, PhD, Medical Department M (Endocrinology and Diabetes), Århus Sygehus, Århus University Hospital, DK-8000 Århus C, Denmark. E-mail: ch.gravholt{at}dadlnet.dk

Abstract

Continuous glucose monitoring (CGM) is being explored using several types of glucose sensors. Some are designed for subcutaneous adipose tissue. It is important to determine to which extent these glucose fluctuations in different tissues reflect changes taking place in the central nervous system, where glucose sensing is thought to occur. We studied the ability of subcutaneous adipose interstitial fluid measurements to parallel glucose propagations in blood, muscle, and central nervous system (CNS) during hyper- and hypoglycemia. A subcutaneous CGM system was applied in the CNS, subcutaneous adipose tissue, and skeletal muscle of nine Vietnamese potbellied pigs, and data were compared with frequent sampling in blood. Alterations in glucose levels were induced with intravenous glucose and insulin. During hyperglycemia, no difference was detected in delay between blood and interstitial glucose levels in subcutaneous adipose tissue (18.0 ± 0.8 min), muscle (18.0 ± 0.9 min), and CNS (20.3 ± 1.2 min), respectively. During hypoglycemia, we found no time difference between interstitial parameters in the three tissues. However, the amplitude of glucose changes varied considerably, with a smaller magnitude of glucose change taking place in the brain. The timing of glucose excursions in subcutaneous adipose tissue and muscle reflect excursions in CNS. The reduced magnitude of glucose excursions in the brain suggests that different mechanisms of glucose transport are operative in CNS compared with subcutaneous adipose tissue and muscle.

Footnotes

  • C.B.D. and H.Ø. have received honoraria from Roche Diagnostics. J.S.C. has received honoraria and grant/research support from Roche Diagnostics.

    The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

    • Accepted March 2, 2005.
    • Received August 31, 2004.
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